A braking device for a vehicle includes a cylinder, a master piston having a pressure applying piston portion and a servo pressure receiving portion, an input piston, a pressure accumulating device, a pilot pressure generating device, and a regulator having a first piston slidably fitted into a housing and dividing an inside of the housing into a first pilot chamber and a servo pressure generating chamber, a valve mechanism connecting the servo pressure generating chamber with the pressure accumulating device or a reservoir in response to movement of the first piston, and a second piston fitted into the housing and dividing the inside of the housing into the first pilot chamber and a second pilot chamber, wherein the second piston is formed so that an end surface thereof exposed to the first pilot chamber has a larger pressure-receiving surface area than an end surface exposed to the second pilot chamber.